


what's yours is mine

by ambersagen



Series: Dean/Cas/Lucifer Verse [1]
Category: Supernatural
Genre: Cas and Lucifer are twins, Child Abuse, John Winchester's A+ Parenting, M/M, Mentions of Underage Sex, Polyamory, Twincest, implied bottom!dean, implied top!Lucifer, teenage making out
Language: English
Status: Completed
Published: 2016-05-24
Updated: 2016-05-24
Packaged: 2018-06-10 08:39:23
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,216
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6948265
Author URL: https://archiveofourown.org/users/ambersagen/pseuds/ambersagen
Summary: <blockquote class="userstuff">
              <p>Dean/Cas/Lucifer for Polyamourous month.<br/>Castiel and Lucifer are twins. Dean never got the message that Lucy is the evil twin.</p>
            </blockquote>





	what's yours is mine

**Author's Note:**

  * For [TheAuthorGod](https://archiveofourown.org/users/TheAuthorGod/gifts).



Everyone knew that of the two Novak twins, Lucifer was the evil one and Castiel was the angel. It was kind of obvious that with a name like Lucifer the eldest twin was destined to be trouble. From the beginning he was the child who wouldn’t finish his vegetables, who threw a crying, screaming fit when he was told he couldn’t have a puppy, and he was the first child in his grade level in middle school to get sent to the principle for starting off a ten child fistfight (although he was released with a three day suspension because no one could actually prove he threw a single punch, much less started the whole fight). 

There was one person who didn’t get that memo though.

Dean Winchester, who was plenty of trouble in his own right and Castiel’s not so secret boyfriend, never gave Lucy the fear and respect that he felt was his due. 

Dean didn’t care that while Cas was a straight A student who did band after class and worked in the community garden in the evenings while Lucifer was setting up a pyramid scheme in the school cafeteria revolving around the recent school ban on vending machine items and the student population’s desperate need for soda. He treated Lucifer with the same disrespect for boundaries that he and Cas shared, much to the bafflement of others who were confused at seeing Dean draping himself over both twins laps on movie night or snatching food off of Cas and Lucy equally at lunch.

After Dean and Cas started dating in freshman year of high school Dean had basically transplanted himself into the Novak’s household. The twin’s parents, while being concerned at first about their son coming out and suddenly having a boy over 24/7, were soon swayed by Dean’s southern manners and dazzling smile. His yes sirs and thank you ma’ams quickly guaranteed him a place at the Novak dinner table most nights and earned the trust of the elder Novaks to the point where even sleepovers were allowed, provided the door stayed open. Which, as the twins discovered after months of concerned questioning from Cas and outright spying from Lucy, was probably one of the best things that could happen for Dean.

When Dean wasn’t hanging out with the twins he lived with his father. His parents had divorced when he was four, and according to Crowley, who Lucy hired to look into Dean’s past when he couldn’t get anything out of the boy himself, Dean’s father had gained custody of his eldest son simply to spite his wife. John Winchester was a bitter, unemployed drunk, and probably the only one in Lawrence who didn’t know that his son was not only practically living over at the Novak’s but was also currently dating their youngest son. In this case however, drunken and indifferent ignorance was bliss for the trio, and Dean spent several happy years playing third to the twins.

It wasn’t a peace meant to last.

“Cas, you’d better not be wanking in there,” Lucifer yelled, banging unannounced into his brother’s room. If he was going to be asked to play messenger then he was going to damn well make sure everyone regretted it. “Mom wants you to give Angel a bath, dumb cat got into the garbage-” he froze, half in the room, one arm awkwardly out as if trying to close the door on his own intrusion.

Dean and Cas sat in front of him on the bed, petrified. Cas was half straddling Dean as red soaked into the t-shirt he had pressed to his boyfriend’s head where Lucifer could see several open cuts bleeding sluggishly into a black eye.

“Don’t tell mom,” Cas said, hands tightening on Dean as he moved to shield him from his brother. 

Lucy turned, closing the door firmly behind him. He stood there for a moment, back to his brother and his brother’s bloodied boyfriend. He was trembling slightly, but when he turned there was rage on his face and not laughter. 

“I’m going to  _ kill _ him,” Lucy said, moving toward the pair with a dark glint in his eyes. He reached towards Dean, who flinched away. Muttering to himself he elbowed Cas aside, taking the t-shirt from him to hold to Dean’s head. “Go get the first aid kit from Gabe’s room,” he ordered Cas, who jumped up with a slightly dazed look on his face. “And for fucks sake, if you don’t want to tell mom about this then you had better come up with an excuse for Dean to stay over tonight.”

“Right,” Cas said, voice shaking slightly as he looked between Dean and his brother. “I’ll just -I’ll  go do that.”

Lucy rolled his eyes. “Go Asstiel, I won’t let anything happen to Dean while you’re out,” He glowered as Dean flinched at the touch of cloth on his wounds. “Anything else that is,” he said, hands gentling even as his expression darkened. 

Lucifer wasn’t under any illusions as to how Dean got his injuries. The fear in his face when Lucifer had walked in told him everything. Most of Lawerence thought John was a harmless if neglectful drunk, but anyone who knew Dean knew there were plenty of days he slunk into school black and blue from a night of staying in.

“I don’t get it,” Dean said, just as the silence of Cas’ departure set in. He kept his eyes firmly on his knees. “Why do you even care, man?”

With the agility of a cat Lucifer sprang forward, pushing Dean back onto the pillows of Cas’ nest like bed. “Get this through your skull, Winchester. If you belong to Cas then you belong to me. We’ve shared everything all our lives and I’m not about to let him stop now. And since you are ours that means  _ no one else gets to touch you, _ ” his fingers traced across Dean’s forehead, finger following trails of blood down to his startled green eyes. Through the hand he pressed to Dean’s chest he could feel the boy was barely breathing. 

“I’m going to kiss you now,” he rumbled, voice just barely above a whisper. “If you have a problem with that then you had better say something now.”

“Please,” Dean breathed, eyes fluttering shut as Lucifer pressed his lips carefully to the corner of his mouth, teasing and licking his way into Dean’s mouth, bloody cloth forgotten as they clutched at each other.

“When Cas gets back,” Lucifer said, breath hot on Dean’s spit slick lips. “We’re going to patch you up and then I’m going to teach you who you belong to,” his tongue trailed up Dean’s brow, earning him a whimper as he followed a drop of blood across his face. “Cas has been far too greedy keeping you to himself this long. I told him you would have us both if we only offered but he didn’t want to scare you away.”

He leaned in, bracing himself on his forearms over Dean, who stared up at him with awe. “You are ours, Dean Winchester,” He looked down at Dean with an almost predatory glint in his eyes. “And I think it’s time we show you why nobody will  _ ever _ be allowed hurt you again.”

 

**Author's Note:**

> Comments fuel me. Please feed the author.
> 
> Come say hello. I am a lonely person.  
> ambersagen.tumblr.com


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